The implementation by interception is a solution based on hardware placed between the Main Distributor and the Telephone Exchange. Because of its location, the solution is suitable both for digital exchanges and analog exchanges as well. Despite this advantage, it is not recommended as the preferred option. The reason lies in the fact that its installation requires substantial changes in the existing infrastructure of the telephone exchange, specifically in the main distributor and the connections to the exchange. Besides, this option does not allow the implementation of the substitution of the invention-to-dial tone by the prerecorded advertisement scheme.